Water Heater Sizing Formula:
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Definition: This calculator determines the appropriate size (in gallons) of an electric water heater based on peak water demand and a safety factor.
Purpose: It helps homeowners and professionals select the right water heater capacity to meet household needs efficiently.
The calculator uses the formula:
Where:
Explanation: The peak demand is multiplied by a safety factor to ensure adequate hot water supply during high usage periods.
Details: Correct sizing prevents running out of hot water during peak usage while avoiding excessive energy costs from an oversized unit.
Tips: Enter your peak hot water demand in gallons and the desired safety factor (default 1.25). All values must be positive numbers.
Q1: How do I determine my peak demand?
A: Add up the hot water usage of all appliances/fixtures that might run simultaneously (shower, dishwasher, washing machine, etc.).
Q2: Why is the safety factor typically 1.25?
A: This 25% buffer accounts for variations in usage patterns and recovery rates.
Q3: When would I use a different safety factor?
A: Use higher factors (1.5) for large families or commercial applications, lower factors (1.1) for single users.
Q4: Does this work for tankless water heaters?
A: No, tankless units are sized by flow rate (GPM) and temperature rise needed.
Q5: How does recovery rate affect sizing?
A: Faster recovery units can sometimes be sized slightly smaller, but this calculator provides a conservative estimate.